The present invention relates to a call process of a subscriber through a corresponding link when a link connecting each node (hereinafter referred to as a trunk link) is cut off in a switching network.
Assuming that subscribers A and B are talking over the telephone through a node 3 as shown in FIG. 1, if a trunk link connecting the node 3 to a node 4 is cut off, then a message of "link cut off" is transmitted to the subscribers A and B and a telephone call is disconnected. In this case, the disconnection of the trunk link can be caused by excessive errors, excessive loss of a message by the increase of load, etc. as well as the disconnection of a line. However, in FIG. 1, since there are another paths, for example, such as a path through a node 5 capable of speaking on the telephone between the subscribers A and B, it is undesirable to cut off a telephone call. In other words, since a decentralized switching network has various paths for connecting a specific node to another, even if a link between specific nodes is disconnected, a telephone call is possible without disconnecting a call.